1. Field of the Invention
The invention relates generally to an authentication system employing near field communication (NFC) techniques, and more particularly to a NFC device, an authentication system using the NFC device, and an authentication method thereof.
2. Description of Related Art
Currency and monetary transaction systems for small payments in situations such as purchasing public transportation fares, tickets for movies or other spectacles, or drinks and magazines at a store are very inconvenient and clumsy for the consumer. The inconveniences may be due to the consumer not carrying enough change to purchase the needed product, or that the consumer requires exchange of a large bill to complete the transaction. However, after the storekeeper exchanges the large bill, the consumer is left with coins and bills of smaller value. As a result, the consumer often feels inconvenienced carrying and managing change when using bills and coins to make small purchases.
In light of the foregoing, transaction systems using contactless cards have gradually replaced the cash and coin transaction systems, thereby reducing the inconveniences of carrying and managing change for the user. As an example, contactless cards based on radio frequency identification (RFID) techniques have replaced cash in many places to become a popular method of payment and monetary transaction, due to the ease of operation and the gradual maturity of the related techniques. However, in order to record the added or deducted monetary value on a same contactless card, many RFID based contactless card payment methods write and store transaction data directly into the RFID tag in the card. This method of recording monetary value on the RFID tag lacks a third party as the independent authority for authenticating the transaction. Moreover, from a security standpoint, this method also poses a security risk which can inflict financial losses for the contactless card holders or the goods and services providers.
In addition, as mobile communication devices (e.g., cell phones) become popular, RFID tags are starting to be combined with these mobile communication devices to serve as another method to pay for small transactions. However, this method of payment cannot be used on regular cell phones without NFC capabilities. For RFID tags to be applicable in most of the mobile communication devices, NFC specifications must be built in the cell phone (e.g., the Nokia NFC cell phone). Moreover, due to the negative effects (e.g., magnetic interference and electromagnetic interference) on the RFID tags caused by the internal circuitry, battery, and antenna of the mobile communication device, this type of RFID tags is likely to fail to operate or generate unanticipated errors and result in unsuccessful transactions. Therefore, it is vitally important to improve the security problem and the unreliable operation of the RFID tagging technique used in the contactless monetary transactions.